It is that photographic images having very high contrast can be formed by using a certain kind of a silver halide photographic material and such a photographic image-forming material and development processes therefor have been used in the field of photomechanical process.
For example, it is known to obtain line images or dot images having a high contrast and a high blackened density, wherein the image portions and non-image portions are clearly distinguished from each other, by processing a lith-type silver halide photographic material containing silver chlorobromide (having a silver chloride content of at least 50%) with a hydroquinone developer having a very low effective concentration (usually less than about 0.1 mole/liter) of sulfite ions. However, the aforesaid developer is very unstable and subject to air oxidation due to the low sulfite concentration in the developer, and hence for keeping the activity of the developer, various efforts and proposals have been made at present.
Accordingly, an image-forming system capable of improving the stability in the aforesaid development process (i.e., in a lith development process) and obtaining the photographic characteristics of a super-high contract by developing a silver halide photographic material using a developer having a high storage stability has been desired and systems of forming negative images having a super-high contrast of over 10 in gamma (.gamma.) by developing surface latent image-type silver halide photographic materials containing specific acylhydrazine compounds using a developer having pH of from 11.0 to 12.3, containing at least 0.15 mole/liter of a sulfite preservative, and good storage stability are proposed as described in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,272,606, 4,311,781, 4,269,929, and 4,650,746. The new image-forming systems have the feature that silver iodo-bromide and silver chloroiodobromide can be also used, while in a conventional super-high contrast image-forming system, only silver chlorobromide having a high silver chloride content can be used.
As the hydrazine compound which is used for such a super-high contrast image-forming system, various kinds of compounds have been described, such as in the aforesaid U.S. patents. However, many of these hydrazine compounds give a high sensitivity, a high contrast, and the high maximum density (Dmax), but have a disadvantage in that they cause an undersirable phenomenon called "black pepper" or "Black pepper spot" by infectious development. Also, it is known that hydrazine compounds having a group adsorbing to silver halide grains are highly active contrast-increasing agents capable of increasing contrast by a small addition amount thereof, but they have a disadvantage of causing extensive black pepper spots.